The positive predictive value of PI-RADS 4 lesions stratified by lesion number in biopsy naïve men

29 Background: To assess the positive predictive value (PPV) of PI-RADS 4 lesions stratified by suspicion for tumor multi-focality. Methods: Between April 2015 and July 2016, 62 biopsy naïve men with at least one PI-RADS 4 lesion underwent mpMRI/US fusion biopsy. Patients were placed into group 1 if they had a single lesion, group 2 if they had an additional PI-RADS 3 or 2 lesion, and group 3 if they had an additional PI-RADS 4 or 5 lesion. Image interpretation was performed prospectively and assessed using PI-RADS version 2. The ANOVA and chi-square tests were used to assess differences between continuous and categorical variables, respectively. Results: Using systematic and targeted biopsy combined, the overall and GS ≥ 7 cancer detection rate for the entire cohort was 80.6% (50/62), and 53.2% (33/62), respectively. There were a total of 88 lesions with 26,14, and 48 lesions in groups 1,2, and 3, respectively. There were no significant differences in mean age, PSA density, race, or lesion location between groups; p = 0.107, p = 0.694, p = 0.511, and p = 0.558, respectively. The PPV for any prostate cancer was 65.4% (17/26), 100% (14/14), and 90% (43/48) for groups 1,2, and 3 respectively (p = 0.005). The PPV for GS ≥ 7 was 42% (11/26), 50% (7/14), and 75% (36/48) for groups 1,2, and 3, respectively (p = 0.001). Conclusions: Our data indicate that the PPV for a PI-RADS category assessment score of 4 may be influenced by tumor multi-focality on imaging. Further assessment with increased sample size will be useful to confirm our initial results.